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- Author or Editor: H.G. Hughes x
Experiments were conducted in the spring and fall of 1967 and the spring of 1968 to determine harvest indices and to evaluate the rate of fruit development and changing grade sizes for both white- and black-spined cucumbers. White-spined ‘Southern Cross’ and black-spined ‘Piccadilly’ were used. Per-acre plant populations in the order of 100,000 in the spring and 70,000 in the fall were established using gynoecious cultivars. The first plots were harvested when only a few marketable fruits were present; subsequent plots were harvested at 2- or 3-day intervals for a total of 8 per experiment. The single deviation from this was the 7-day interval between the seventh and eighth harvests of the fall experiment.
Maximum returns per acre occurred when the proportion of fruit greater than 2 inches in diameter ranged from 14 to 31% of the total weight. It is suggested that plantings should be harvested as soon as fruits larger in diameter than 2 inches are found in the field.
In spring plantings the percentage of plants bearing fruit reached 91 whereas those in the fall trial reached 98. The average number of fruit per plant did not exceed 1.27 in any trial.
Carbon dioxide concentrations measured within and above a strawberry plant (Fragaria × ananassa) canopy were significantly higher during enrichment with carbonated water or 900 kg CO2 ha-1 hr-1 applied as gas. Both sources were applied to the base of the plants through drip irrigation tubing under a black polyethylene mulch (0.025 mm) covering or over bare unmulched soil. Mulch affected the concentrations at the top of the strawberry canopy differently for the two sources of CO2 enrichment. Carbonated water was found to reduce the pH of the calcareous soil at the research site (pH 8.2) during and between irrigations. The greatest single pH reduction was 2.6 pH units during irrigation measured in mulched soil; significant soil pH reductions were detected as long as 28 days after irrigation underneath the mulch. Soil pH “duration” below pH 7.4 was 70% greater considering mulch and carbonated water vs. no mulch and carbonated water irrigation.
Pollen from Clianthus formosus (G. Don) Ford and Vickery was tested for viability after desiccation and exposure to low temperatures. Desiccation for 3 hours before freezing at –180C was sufficient for maintaining pollen germination. Pollen dried for a longer time showed reduced germination when plated directly. However, when pollen was rehydrated by exposure to high humidity before plating, germination was not reduced.
Five color types of Alstroemeria ligtu Linn hybrids from one seed source were examined cytogenetically. The somatic chromosome numbers were all 2n = 2x = 16. Karyotype analysis revealed that all five plants had the same chromosome constitution. Chromosome pairs 2,3,5, and 8 had satellites. Chromosome complements of the A. ligtu hybrid were unique in that they contained two pairs of satellite metacentric chromosomes that were not found in any Alstroemeria cultivars.
The use of random amplified polymorphic DNA (RAPD) markers has been shown to be a potentially useful technique for identifying buffalograss breeding lines. Analysis of RAPD markers has also revealed considerable variation within, as well as among, each of four natural buffalograss populations surveyed. Identification of genetic markers for quantitative traits, such as physiological components of tolerance to salt stress, can provide important information for plant improvement programs. The objectives of this study were to develop DNA fingerprints for buffalograss clones selected from an in vitro seedling screening program for survival at high NaCI (200–250 mM) levels, identify markers for future analysis, and assess the variability among the lines. DNA was extracted from leaves of 10 salt-selected and 15 non-selected buffalograss clones. Fifty-two 10-mer primers were screened for ability to produce bands with DNA from four clones as visualized on ethidium-stained agarose gels. Bands were most reproducible with a genomic template DNA concentration of 1 ng–μl–1 reaction volume. Primers selected for ability to produce a moderate number of clear bands were used to produce RAPD profiles of the 25 clones. Abundant polymorphism to distinguish among clones was found. Four primers produced a total of 45 polymorphic markers. The primer 5′-CGGAGAGCCC-3′ produced 11 readily scored markers, allowing identification in 94.67% of pair-wise comparisons. As a group, RAPD profiles of salt-selected clones are more variable than non-selected clones from the same population; however, no unique pattern of markers generated by primers screened to date differentiates all salt-selected clones from the non-selected group.
Red raspberry (Rubus idaeus L.) is prone to a “white drupelet” disorder on the sun-exposed side of the fruit, largely during those harvest periods when daytime temperatures exceed about 33°C. In mid-August, more than 40% of the fruit were affected. Three types of shade covers (30% and 60% black shade fabric and 25% shade white polyester), placed over raspberry plots for 1 to 3 weeks prior to fruit harvest, reduced the amount of solar-injured fruit from 41% in unshaded plots to between 8% and 16%. Fruit surface temperature was reduced about 4° by both black shade fabrics, but only 1° by the polyester cover. Fans cooled fruit by about 2°, but the reduction in solar injury was less than with shade covers.
Carbonated water (CW) application has enhanced yields of tomato. However, little is known about the mechanism of this response. Our objectives were to determine if strawberry would respond to CW application and the effect of soil pH modification on the expression of a yield response. Two different soils were used; a calcareous soil (5% CaCO3, pH 7.9), with a Zn content 0.8 ppm and a non-calcareous soil (< 1% CaCO3, pH 6.5) with a Zn content 8.8 ppm. The carbonated water temporarily lowered the pH of the calcareous soil to 6.7 and the non-calcareous soil to 5.9, at both extremes of the optimal range (6.0-6.7) for strawberry. Application of carbonated water increased production of marketable fruit as compared to the tap water control on both soils, and the magnitude of the response to CW was similar for both soils. Soil and water treatment effects on leaf tissue Zn levels will also be discussed.